The present invention relates to motion control systems and more specifically to control systems that use cameras to identify locations of parts during an automated process and uses the location information to modify process control where communication between a motion controller and cameras is via the Ethernet.
Automated systems are used in many different industries including manufacturing, shipping, testing, etc. In many applications parts (or products) are moved about within an environment and between locations using web based systems where, as the label implies, flexible webs are provided to transfer parts from one location to another. Here, in many cases, the webs are supported on spindles driven by servo motors to move the webs and parts supported thereon through a process from station to station until the process is complete. The servo motors are controlled by motor drives that control motor operating characteristics such as speed, acceleration and deceleration, etc. Coordination between drives is handled by a motion controller that synchronizes drive control in an appropriate fashion.
One problem with automated systems that employ web based part transfer systems is that the webs often slip relative to the supporting spindles. When a web slips, the locations of parts within the automated process (i.e., with respect to a drive system) cannot be precisely determined solely as a function of how the servos are controlled. In cases where webs slip relative to servo motors, some form of feedback is needed to ascertain the locations of parts with respect to the drive system and overall process.
One feedback solution for determining locations of parts in a web based drive system has been to provide photo sensors at various locations along the path of a web to detect part presence. Photo sensor feedback signals are provided to the motion controller which uses the position feedback signals to adjust drive system operation accordingly.
While photo sensors can provide needed position feedback, systems that include photo sensors have several drawbacks. First, in many applications the location of a part/product within a region has to be tracked precisely throughout the region. To track part location throughout a region a large number of photo sensors are needed and therefore the photo sensor solution can be expensive.
Second, for a photo sensor to sense part location, the sensor must be positioned very close to the path along which the part travels. For this reason the process associated with installing photo sensors is tedious and time consuming. Exacerbating matters, when a process has to be modified such that required part locations have to be changed, photosensor positions have to be altered which increases costs appreciably.
Third, many products are difficult to locate using photo sensors and therefore photo sensors are not suitable for many applications.
Thus, there is a need for a system that can be used to determine part locations in web based drive systems that overcomes the problems associated with systems that rely on photo sensors.